Nadia ate 2 slices of pie. Luis ate 1 slice. If Nadia ate $\dfrac{2}{5}$ of the pie, what fraction of the pie is remaining?
Solution: If 2 slices represent $\dfrac{2}{5}$ of the pie, there must have been a total of 5 slices. $\text{fraction of pie remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 3 slices, which leaves 2 out of 5 slices remaining. There is $\dfrac{2}{5}$ of the pie remaining.